diff --git a/README.md b/README.md
index da06519..4244087 100644
--- a/README.md
+++ b/README.md
@@ -64,9 +64,9 @@ the the function call is excluded only if the type of the first argument is `TYP
 
 An example of an exclude file is:
 
-    io/ioutil.ReadFile
     io.Copy(*bytes.Buffer)
     io.Copy(os.Stdout)
+    os.ReadFile
 
     // Sometimes we don't care if a HTTP request fails.
     (*net/http.Client).Do
diff --git a/errcheck/errcheck_test.go b/errcheck/errcheck_test.go
index d870ed2..a588597 100644
--- a/errcheck/errcheck_test.go
+++ b/errcheck/errcheck_test.go
@@ -2,7 +2,6 @@ package errcheck
 
 import (
 	"fmt"
-	"io/ioutil"
 	"os"
 	"path"
 	"regexp"
@@ -120,7 +119,7 @@ package custom
 `
 	)
 
-	tmpGopath, err := ioutil.TempDir("", "testbuildtags")
+	tmpGopath, err := os.MkdirTemp("", "testbuildtags")
 	if err != nil {
 		t.Fatalf("unable to create testbuildtags directory: %v", err)
 	}
@@ -132,16 +131,16 @@ package custom
 		os.RemoveAll(tmpGopath)
 	}()
 
-	if err := ioutil.WriteFile(path.Join(testBuildTagsDir, "go.mod"), []byte("module github.com/testbuildtags"), 0644); err != nil {
+	if err := os.WriteFile(path.Join(testBuildTagsDir, "go.mod"), []byte("module github.com/testbuildtags"), 0644); err != nil {
 		t.Fatalf("Failed to write testbuildtags go.mod: %v", err)
 	}
-	if err := ioutil.WriteFile(path.Join(testBuildTagsDir, "custom1.go"), []byte(testBuildCustom1Tag), 0644); err != nil {
+	if err := os.WriteFile(path.Join(testBuildTagsDir, "custom1.go"), []byte(testBuildCustom1Tag), 0644); err != nil {
 		t.Fatalf("Failed to write testbuildtags custom1: %v", err)
 	}
-	if err := ioutil.WriteFile(path.Join(testBuildTagsDir, "custom2.go"), []byte(testBuildCustom2Tag), 0644); err != nil {
+	if err := os.WriteFile(path.Join(testBuildTagsDir, "custom2.go"), []byte(testBuildCustom2Tag), 0644); err != nil {
 		t.Fatalf("Failed to write testbuildtags custom2: %v", err)
 	}
-	if err := ioutil.WriteFile(path.Join(testBuildTagsDir, "doc.go"), []byte(testDoc), 0644); err != nil {
+	if err := os.WriteFile(path.Join(testBuildTagsDir, "doc.go"), []byte(testDoc), 0644); err != nil {
 		t.Fatalf("Failed to write testbuildtags doc: %v", err)
 	}
 
@@ -229,7 +228,7 @@ require github.com/testlog v0.0.0
 	}`
 
 	// copy testvendor directory into directory for test
-	tmpGopath, err := ioutil.TempDir("", "testvendor")
+	tmpGopath, err := os.MkdirTemp("", "testvendor")
 	if err != nil {
 		t.Fatalf("unable to create testvendor directory: %v", err)
 	}
@@ -241,16 +240,16 @@ require github.com/testlog v0.0.0
 		os.RemoveAll(tmpGopath)
 	}()
 
-	if err := ioutil.WriteFile(path.Join(testVendorDir, "go.mod"), []byte(testVendorGoMod), 0755); err != nil {
+	if err := os.WriteFile(path.Join(testVendorDir, "go.mod"), []byte(testVendorGoMod), 0755); err != nil {
 		t.Fatalf("Failed to write testvendor go.mod: %v", err)
 	}
-	if err := ioutil.WriteFile(path.Join(testVendorDir, "main.go"), []byte(testVendorMain), 0755); err != nil {
+	if err := os.WriteFile(path.Join(testVendorDir, "main.go"), []byte(testVendorMain), 0755); err != nil {
 		t.Fatalf("Failed to write testvendor main: %v", err)
 	}
 	if err := os.MkdirAll(path.Join(testVendorDir, "vendor/github.com/testlog"), 0755); err != nil {
 		t.Fatalf("MkdirAll failed: %v", err)
 	}
-	if err := ioutil.WriteFile(path.Join(testVendorDir, "vendor/github.com/testlog/testlog.go"), []byte(testLog), 0755); err != nil {
+	if err := os.WriteFile(path.Join(testVendorDir, "vendor/github.com/testlog/testlog.go"), []byte(testLog), 0755); err != nil {
 		t.Fatalf("Failed to write testlog: %v", err)
 	}
 
@@ -336,7 +335,7 @@ require github.com/testlog v0.0.0
 	}`
 
 	// copy testvendor directory into directory for test
-	tmpGopath, err := ioutil.TempDir("", "testvendor")
+	tmpGopath, err := os.MkdirTemp("", "testvendor")
 	if err != nil {
 		t.Fatalf("unable to create testvendor directory: %v", err)
 	}
@@ -348,16 +347,16 @@ require github.com/testlog v0.0.0
 		os.RemoveAll(tmpGopath)
 	}()
 
-	if err := ioutil.WriteFile(path.Join(testVendorDir, "go.mod"), []byte(testVendorGoMod), 0755); err != nil {
+	if err := os.WriteFile(path.Join(testVendorDir, "go.mod"), []byte(testVendorGoMod), 0755); err != nil {
 		t.Fatalf("Failed to write testvendor go.mod: %v", err)
 	}
-	if err := ioutil.WriteFile(path.Join(testVendorDir, "main.go"), []byte(testVendorMain), 0755); err != nil {
+	if err := os.WriteFile(path.Join(testVendorDir, "main.go"), []byte(testVendorMain), 0755); err != nil {
 		t.Fatalf("Failed to write testvendor main: %v", err)
 	}
 	if err := os.MkdirAll(path.Join(testVendorDir, "vendor/github.com/testlog"), 0755); err != nil {
 		t.Fatalf("MkdirAll failed: %v", err)
 	}
-	if err := ioutil.WriteFile(path.Join(testVendorDir, "vendor/github.com/testlog/testlog.go"), []byte(testLog), 0755); err != nil {
+	if err := os.WriteFile(path.Join(testVendorDir, "vendor/github.com/testlog/testlog.go"), []byte(testLog), 0755); err != nil {
 		t.Fatalf("Failed to write testlog: %v", err)
 	}
 
diff --git a/errcheck/excludes.go b/errcheck/excludes.go
index c1b8f46..a783b5a 100644
--- a/errcheck/excludes.go
+++ b/errcheck/excludes.go
@@ -3,7 +3,7 @@ package errcheck
 import (
 	"bufio"
 	"bytes"
-	"io/ioutil"
+	"os"
 	"strings"
 )
 
@@ -56,7 +56,7 @@ var DefaultExcludedSymbols = []string{
 func ReadExcludes(path string) ([]string, error) {
 	var excludes []string
 
-	buf, err := ioutil.ReadFile(path)
+	buf, err := os.ReadFile(path)
 	if err != nil {
 		return nil, err
 	}
diff --git a/errcheck/testdata/src/a/main.go b/errcheck/testdata/src/a/main.go
index a531c55..f34c698 100644
--- a/errcheck/testdata/src/a/main.go
+++ b/errcheck/testdata/src/a/main.go
@@ -6,9 +6,9 @@ import (
 	"bytes"
 	"crypto/sha256"
 	"fmt"
-	"io/ioutil"
 	"math/rand"
 	mrand "math/rand"
+	"os"
 )
 
 func a() error {
@@ -150,7 +150,7 @@ func main() {
 	mrand.Read(nil)
 	sha256.New().Write([]byte{})
 
-	ioutil.ReadFile("main.go") // want "unchecked error"
+	os.ReadFile("main.go") // want "unchecked error"
 
 	var emiw ErrorMakerInterfaceWrapper
 	emiw.MakeNilError() // want "unchecked error"
diff --git a/testdata/main.go b/testdata/main.go
index 44d4ac4..0f57c43 100644
--- a/testdata/main.go
+++ b/testdata/main.go
@@ -5,9 +5,9 @@ import (
 	"crypto/sha256"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"math/rand"
 	mrand "math/rand"
+	"os"
 )
 
 func a() error {
@@ -152,7 +152,7 @@ func main() {
 	pr.CloseWithError(nil)
 	pw.CloseWithError(nil)
 
-	ioutil.ReadFile("main.go") // UNCHECKED
+	os.ReadFile("main.go") // UNCHECKED
 
 	var emiw ErrorMakerInterfaceWrapper
 	emiw.MakeNilError()
diff --git a/testdata/main_test.go b/testdata/main_test.go
index 79e9659..2ed3d06 100644
--- a/testdata/main_test.go
+++ b/testdata/main_test.go
@@ -3,10 +3,9 @@ package main
 import (
 	"bytes"
 	"crypto/sha256"
-	"io/ioutil"
 	"math/rand"
 	mrand "math/rand"
-
+	"os"
 	"testing"
 )
 
@@ -84,7 +83,7 @@ func TestFunc(tt *testing.T) {
 	mrand.Read(nil)
 	sha256.New().Write([]byte{})
 
-	ioutil.ReadFile("main.go") // UNCHECKED
+	os.ReadFile("main.go") // UNCHECKED
 
 	var emiw ErrorMakerInterfaceWrapper
 	emiw.MakeNilError()